Pelosi: No UK trade deal if Brexit undermines Good Friday accord
Nancy Pelosi speaks to reporters (CNN/screen grab)

An American trade pact with Britain is doomed if the latter's withdrawal from the EU undermines the Northern Ireland peace accord, US House Speaker Nancy Pelosi warned Wednesday.

"Whatever form it takes, Brexit cannot be allowed to imperil the Good Friday Agreement, including the seamless border between the Irish Republic and Northern Ireland," Pelosi, the top Democrat in Congress, said in a statement.

"If Brexit undermines the Good Friday accord, there will be no chance of a US-UK trade agreement passing the Congress."

The 1998 Good Friday Agreement brought the decades-old Northern Ireland conflict to an end. But how to handle Northern Ireland has emerged as a core issue for Brexit negotiators.

Because Northern Ireland, which is a part of the United Kingdom, shares a border with Ireland, a part of the EU, critics have warned that Brexit might require reimposing a hard border on the island -- essentially upending the agreement that has kept peace in Northern Ireland for the past two decades.

Goods and people freely cross the border, as both countries are currently members of the EU.

The withdrawal agreement negotiated last year between London and Brussels contains a "backstop" plan to maintain this situation whatever happens with Brexit.

However, British MPs have rejected it three times and new Prime Minister Boris Johnson warns the backstop must go or Britain will leave the EU on October 31 without any deal.

Pelosi, a master legislator, strongly signalled that Republicans would join her Democrats in opposing a trade pact if Brexit undermines the peace deal.

"The peace of the Good Friday Agreement is treasured by the American people and will be fiercely defended on a bicameral and bipartisan basis in the United States Congress," she said.

The Republican co-chair of the Friends of Ireland group in the US Congress, Pete King, reportedly said jeopardizing the open border was a "needless provocation" over which his party would have no hesitation defying Trump.

Those in Congress with a strong belief in Northern Ireland and the Good Friday agreement "would certainly be willing to go against the president," King told The Guardian.

On Monday US National Security Advisor John Bolton, a hawkish Trump aide, said Washington wanted to "move very quickly" on the trade pact after Britain exits the EU.